The ability to obtain electrical activity of the human heart from the surface of the skin that was effectuated by Augustus De'sire Waller in 1887 required the subject's limbs to be submersed in saline. In 1912 Willem Einthoven defined lead positions I, II and III which became known as Einthoven's Triangle. The use of physiological sensors or chest leads for the purpose of collecting electrical data generated by a person's heart in a clinical environment dates back to Charles Wolferth and Francis Wood in 1932. This led to the Wilson Central Terminal, an “indifferent electrode (neutral or grounding electrode)” by Frank Wilson in 1934, and standardized positions and wiring of the chest leads V1-V6 in 1938 that were adopted by the American Heart Association. In 1942 Emanuel Goldberger added limb leads aVR, aVL and aVF, which when combined with leads I-III and V1-V6, create the twelve lead electrocardiograms in use today. Robert Zalenski defined what is now known as leads V4R, V8 and V9 in 1993 creating the 15 lead ECG.
In 1949 physicist Norman Holter invented in the first telemetric cardiac monitoring device or ambulatory electrocardiography device known as the “Holter Monitor”. The original “Holter Monitor” weighed seventy-five pounds. After significant size and weight reductions, it began usage in mainstream clinical environments in the 1960's. The typical “Holter Monitor” in use today weighs less than six ounces and is the most prevalent device used for the diagnosis and monitoring of cardiovascular conditions.
The object of a Holter test is to record the electrical activity of a person's heart for a continuous period of time which ranges between twenty-four and forty-eight hours. It is further the goal to have the test completed while the person conducts his normal daily activities while wearing the testing device. Unfortunately, typical devices in use today are not easily concealed and require placement and hook up onto the person by a skilled technician. They are uncomfortable and restrictive in one's ability to carry out day to day tasks and for sleeping while the test is carried out. As such, it is well known to those in the medical community that patient compliance is minimal at best and a large percentage of patients will call out sick from work or restrict their activities during the testing period. This leads to data being collected in a hybrid situation since it is a variance of the desired daily activity. While the present invention is not specific or limited only to use during ambulatory electrocardiographic testing or Holter Monitoring, a primary use of the present invention is for such monitoring.
The field of electrocardiogram (ECG) testing is comprised of devices that use anywhere from a single channel of data consisting of the placement of two electrodes on a patient's body to a plurality of electrodes that may number as many as eighteen individual electrodes to produce a sixteen lead ECG and any variation in between. Additionally, there exists within the industry numerous algorithms or methods used to obtain ECG's of different lead counts using fewer actual leads attached to the patient. Examples of such algorithms or methods include MEANS and EASI which allow the production of a twelve lead ECG from only three channels of collected data. The EASI method developed by Gordon E. Dower (disclosed in U.S. Pat. No. 4,850,370) derives a twelve lead ECG from the placement of electrodes using lead positions E, A, S and I in addition to a common ground as derived by Ernest Frank Ph.D. in 1956.
Further attention is directed to the state of the current healthcare system in place in the U.S.A. today. The Centers for Disease Control and Prevention (CDC) estimates that the total cost of Healthcare in 2010 surpassed two and a half trillion dollars and that the portion of that sum relating to the diagnosis, treatment and monitoring of cardiovascular related illnesses and diseases exceeds five hundred billion dollars. A significant focus is being placed on the need to establish earlier detection methods while at the same time reducing the costs associated with diagnosis, treatment and monitoring of cardiovascular related illnesses and diseases. One method of accomplishing these goals is to place more devices in the market that do not rely on costly manufacturing methods or need highly trained and costly medical professionals for the use of the devices. The invention described herein accomplishes both of these goals while providing many other benefits to devices currently used in the market place.